Add support for zero-conf and scid-alias (#2224)

This implements lightning/bolts#910.

Co-authored-by: Bastien Teinturier <31281497+t-bast@users.noreply.github.com>

docs/release-notes/eclair-vnext.md

@@ -4,12 +4,88 @@
 
 ## Major changes
 
-Dropped support for version 2 of Tor protocol. That means 
+### Add support for channel aliases and zeroconf channels
+
+:information_source: Those features are only supported for channels of type `AnchorOutputsZeroFeeHtlcTx`, which is the
+newest channel type and the one enabled by default. If you are opening a channel with a node that doesn't run Eclair,
+make sure they support `option_anchors_zero_fee_htlc_tx`.
+
+#### Channel aliases
+
+Channel aliases offer a way to use arbitrary channel identifiers for routing. This feature improves privacy by not
+leaking the funding transaction of the channel during payments.
+
+This feature is enabled by default, but your peer has to support it too, and it is not compatible with public channels.
+
+#### Zeroconf channels
+
+Zeroconf channels make it possible to use a newly created channel before the funding tx is confirmed on the blockchain.
+
+:warning: Zeroconf requires the fundee to trust the funder. For this reason it is disabled by default, and you should
+only enable it on a peer-by-peer basis.
+
+##### Enabling through features
+
+Below is how to enable zeroconf with a given peer in `eclair.conf`. With this config, your node will _accept_ zeroconf
+channels from node `03864e...`.
+
+```eclair.conf
+override-init-features = [
+  {
+    nodeid = "03864ef025fde8fb587d989186ce6a4a186895ee44a926bfc370e2c366597a3f8f",
+    features = {
+      // these features need to be enabled
+      var_onion_optin = mandatory
+      payment_secret = mandatory
+      option_channel_type = optional
+      // dependencies of zeroconf
+      option_static_remotekey = optional
+      option_anchors_zero_fee_htlc_tx = optional
+      option_scid_alias = optional
+      // enable zeroconf
+      option_zeroconf = optional
+    }
+  }
+]
+```
+
+Note that, as funder, Eclair will happily use an unconfirmed channel if the peer sends an early `channel_ready`, even if
+the `option_zeroconf` feature isn't enabled, as long as the peer provides a channel alias.
+
+##### Enabling through channel type
+
+You can enable `option_scid_alias` and `option_zeroconf` features by requesting them in the channel type, even if those
+options aren't enabled in your features.
+
+The new channel types variations are:
+
+- `anchor_outputs_zero_fee_htlc_tx+scid_alias`
+- `anchor_outputs_zero_fee_htlc_tx+zeroconf`
+- `anchor_outputs_zero_fee_htlc_tx+scid_alias+zeroconf`
+
+Examples using the command-line interface:
+
+- open a public zeroconf channel:
+
+```shell
+$ ./eclair-cli open --nodeId=03864e... --fundingSatoshis=100000 --channelType=anchor_outputs_zero_fee_htlc_tx+zeroconf --announceChannel=true
+```
+
+- open a private zeroconf channel with aliases:
+
+```shell
+$ ./eclair-cli open --nodeId=03864e... --fundingSatoshis=100000 --channelType=anchor_outputs_zero_fee_htlc_tx+scid_alias+zeroconf --announceChannel=false
+```
+
+### Remove support for Tor v2
+
+Dropped support for version 2 of Tor protocol. That means:
 
 - Eclair can't open control connection to Tor daemon version 0.3.3.5 and earlier anymore
 - Eclair can't create hidden services for Tor protocol v2 with newer versions of Tor daemon
 
-IMPORTANT: You'll need to upgrade your Tor daemon if for some reason you still use Tor v0.3.3.5 or earlier before upgrading to this release. 
+IMPORTANT: You'll need to upgrade your Tor daemon if for some reason you still use Tor v0.3.3.5 or earlier before
+upgrading to this release.
 
 ### API changes
 
@@ -20,25 +96,33 @@ IMPORTANT: You'll need to upgrade your Tor daemon if for some reason you still u
 
 #### Delay enforcement of new channel fees
 
-When updating the relay fees for a channel, eclair can now continue accepting to relay payments using the old fee even if they would be rejected with the new fee.
-By default, eclair will still accept the old fee for 10 minutes, you can change it by setting `eclair.relay.fees.enforcement-delay` to a different value.
+When updating the relay fees for a channel, eclair can now continue accepting to relay payments using the old fee even
+if they would be rejected with the new fee.
+By default, eclair will still accept the old fee for 10 minutes, you can change it by
+setting `eclair.relay.fees.enforcement-delay` to a different value.
 
-If you want a specific fee update to ignore this delay, you can update the fee twice to make eclair forget about the previous fee.
+If you want a specific fee update to ignore this delay, you can update the fee twice to make eclair forget about the
+previous fee.
 
 #### New minimum funding setting for private channels
 
-New settings have been added to independently control the minimum funding required to open public and private channels to your node.
+New settings have been added to independently control the minimum funding required to open public and private channels
+to your node.
 
-The `eclair.channel.min-funding-satoshis` setting has been deprecated and replaced with the following two new settings and defaults:
+The `eclair.channel.min-funding-satoshis` setting has been deprecated and replaced with the following two new settings
+and defaults:
 
 * `eclair.channel.min-public-funding-satoshis = 100000`
 * `eclair.channel.min-private-funding-satoshis = 100000`
 
-If your configuration file changes `eclair.channel.min-funding-satoshis` then you should replace it with both of these new settings.
+If your configuration file changes `eclair.channel.min-funding-satoshis` then you should replace it with both of these
+new settings.
 
 #### Expired incoming invoices now purged if unpaid
 
-Expired incoming invoices that are unpaid will be searched for and purged from the database when Eclair starts up. Thereafter searches for expired unpaid invoices to purge will run once every 24 hours. You can disable this feature, or change the search interval with two new settings:
+Expired incoming invoices that are unpaid will be searched for and purged from the database when Eclair starts up.
+Thereafter searches for expired unpaid invoices to purge will run once every 24 hours. You can disable this feature, or
+change the search interval with two new settings:
 
 * `eclair.purge-expired-invoices.enabled = true
 * `eclair.purge-expired-invoices.interval = 24 hours`
@@ -77,13 +161,16 @@ Use the following command to generate the eclair-node package:
 mvn clean install -DskipTests
 ```
 
-That should generate `eclair-node/target/eclair-node-<version>-XXXXXXX-bin.zip` with sha256 checksums that match the one we provide and sign in `SHA256SUMS.asc`
+That should generate `eclair-node/target/eclair-node-<version>-XXXXXXX-bin.zip` with sha256 checksums that match the one
+we provide and sign in `SHA256SUMS.asc`
 
-(*) You may be able to build the exact same artefacts with other operating systems or versions of JDK 11, we have not tried everything.
+(*) You may be able to build the exact same artefacts with other operating systems or versions of JDK 11, we have not
+tried everything.
 
 ## Upgrading
 
-This release is fully compatible with previous eclair versions. You don't need to close your channels, just stop eclair, upgrade and restart.
+This release is fully compatible with previous eclair versions. You don't need to close your channels, just stop eclair,
+upgrade and restart.
 
 ## Changelog
 

eclair-core/src/main/resources/reference.conf

@@ -60,9 +60,13 @@ eclair {
     option_dual_fund = disabled
     option_onion_messages = optional
     option_channel_type = optional
+    option_scid_alias = optional
     option_payment_metadata = optional
-    trampoline_payment_prototype = disabled
+    // By enabling option_zeroconf, you will be trusting your peers as fundee. You will lose funds if they double spend
+    // their funding tx.
+    option_zeroconf = disabled
     keysend = disabled
+    trampoline_payment_prototype = disabled
   }
   override-init-features = [ // optional per-node features
     #  {

eclair-core/src/main/scala/fr/acinq/eclair/BlockHeight.scala

@@ -36,6 +36,8 @@ case class BlockHeight(private val underlying: Long) extends Ordered[BlockHeight
   def toInt: Int = underlying.toInt
   def toLong: Long = underlying
   def toDouble: Double = underlying.toDouble
+
+  override def toString() = underlying.toString
   // @formatter:on
 }
 

eclair-core/src/main/scala/fr/acinq/eclair/Eclair.scala

@@ -182,14 +182,18 @@ class EclairImpl(appKit: Kit) extends Eclair with Logging {
   override def open(nodeId: PublicKey, fundingAmount: Satoshi, pushAmount_opt: Option[MilliSatoshi], channelType_opt: Option[SupportedChannelType], fundingFeeratePerByte_opt: Option[FeeratePerByte], announceChannel_opt: Option[Boolean], openTimeout_opt: Option[Timeout])(implicit timeout: Timeout): Future[ChannelOpenResponse] = {
     // we want the open timeout to expire *before* the default ask timeout, otherwise user will get a generic response
     val openTimeout = openTimeout_opt.getOrElse(Timeout(20 seconds))
-    (appKit.switchboard ? Peer.OpenChannel(
-      remoteNodeId = nodeId,
-      fundingSatoshis = fundingAmount,
-      pushMsat = pushAmount_opt.getOrElse(0 msat),
-      channelType_opt = channelType_opt,
-      fundingTxFeeratePerKw_opt = fundingFeeratePerByte_opt.map(FeeratePerKw(_)),
-      channelFlags = announceChannel_opt.map(announceChannel => ChannelFlags(announceChannel = announceChannel)),
-      timeout_opt = Some(openTimeout))).mapTo[ChannelOpenResponse]
+    for {
+      _ <- Future.successful(0)
+      open = Peer.OpenChannel(
+        remoteNodeId = nodeId,
+        fundingSatoshis = fundingAmount,
+        pushMsat = pushAmount_opt.getOrElse(0 msat),
+        channelType_opt = channelType_opt,
+        fundingTxFeeratePerKw_opt = fundingFeeratePerByte_opt.map(FeeratePerKw(_)),
+        channelFlags = announceChannel_opt.map(announceChannel => ChannelFlags(announceChannel = announceChannel)),
+        timeout_opt = Some(openTimeout))
+      res <- (appKit.switchboard ? open).mapTo[ChannelOpenResponse]
+    } yield res
   }
 
   override def close(channels: List[ApiTypes.ChannelIdentifier], scriptPubKey_opt: Option[ByteVector], closingFeerates_opt: Option[ClosingFeerates])(implicit timeout: Timeout): Future[Map[ApiTypes.ChannelIdentifier, Either[Throwable, CommandResponse[CMD_CLOSE]]]] = {

eclair-core/src/main/scala/fr/acinq/eclair/Features.scala

@@ -240,11 +240,21 @@ object Features {
     val mandatory = 44
   }
 
+  case object ScidAlias extends Feature with InitFeature with NodeFeature with ChannelTypeFeature {
+    val rfcName = "option_scid_alias"
+    val mandatory = 46
+  }
+
   case object PaymentMetadata extends Feature with InvoiceFeature {
     val rfcName = "option_payment_metadata"
     val mandatory = 48
   }
 
+  case object ZeroConf extends Feature with InitFeature with NodeFeature with ChannelTypeFeature {
+    val rfcName = "option_zeroconf"
+    val mandatory = 50
+  }
+
   case object KeySend extends Feature with NodeFeature {
     val rfcName = "keysend"
     val mandatory = 54
@@ -278,9 +288,11 @@ object Features {
     DualFunding,
     OnionMessages,
     ChannelType,
+    ScidAlias,
     PaymentMetadata,
-    TrampolinePaymentPrototype,
-    KeySend
+    ZeroConf,
+    KeySend,
+    TrampolinePaymentPrototype
   )
 
   // Features may depend on other features, as specified in Bolt 9.

eclair-core/src/main/scala/fr/acinq/eclair/ShortChannelId.scala

@@ -16,46 +16,71 @@
 
 package fr.acinq.eclair
 
-/**
- * A short channel id uniquely identifies a channel by the coordinates of its funding tx output in the blockchain.
- * See BOLT 7: https://github.com/lightningnetwork/lightning-rfc/blob/master/07-routing-gossip.md#requirements
- */
-case class ShortChannelId(private val id: Long) extends Ordered[ShortChannelId] {
-
-  def toLong: Long = id
-
-  def blockHeight = ShortChannelId.blockHeight(this)
+import fr.acinq.eclair.ShortChannelId.toShortId
 
-  override def toString: String = {
+// @formatter:off
+sealed trait ShortChannelId extends Ordered[ShortChannelId] {
+  def toLong: Long
+  // we use an unsigned long comparison here
+  override def compare(that: ShortChannelId): Int = (this.toLong + Long.MinValue).compareTo(that.toLong + Long.MinValue)
+  override def hashCode(): Int = toLong.hashCode()
+  override def equals(obj: Any): Boolean = obj match {
+    case scid: ShortChannelId => this.toLong.equals(scid.toLong)
+    case _ => false
+  }
+  def toCoordinatesString: String = {
     val TxCoordinates(blockHeight, txIndex, outputIndex) = ShortChannelId.coordinates(this)
     s"${blockHeight.toLong}x${txIndex}x$outputIndex"
   }
-
-  // we use an unsigned long comparison here
-  override def compare(that: ShortChannelId): Int = (this.id + Long.MinValue).compareTo(that.id + Long.MinValue)
+  def toHex: String = s"0x${toLong.toHexString}"
+}
+/** Sometimes we don't know what a scid really is */
+case class UnspecifiedShortChannelId(private val id: Long) extends ShortChannelId {
+  override def toLong: Long = id
+  override def toString: String = toCoordinatesString // for backwards compatibility, because ChannelUpdate have an unspecified scid
 }
+case class RealShortChannelId private(private val id: Long) extends ShortChannelId {
+  override def toLong: Long = id
+  override def toString: String = toCoordinatesString
+  def blockHeight: BlockHeight = ShortChannelId.blockHeight(this)
+  def outputIndex: Int = ShortChannelId.outputIndex(this)
+}
+case class Alias(private val id: Long) extends ShortChannelId {
+  override def toLong: Long = id
+  override def toString: String = toHex
+}
+// @formatter:on
 
 object ShortChannelId {
-
   def apply(s: String): ShortChannelId = s.split("x").toList match {
-    case blockHeight :: txIndex :: outputIndex :: Nil => ShortChannelId(toShortId(blockHeight.toInt, txIndex.toInt, outputIndex.toInt))
+    case blockHeight :: txIndex :: outputIndex :: Nil => UnspecifiedShortChannelId(toShortId(blockHeight.toInt, txIndex.toInt, outputIndex.toInt))
     case _ => throw new IllegalArgumentException(s"Invalid short channel id: $s")
   }
 
-  def apply(blockHeight: BlockHeight, txIndex: Int, outputIndex: Int): ShortChannelId = ShortChannelId(toShortId(blockHeight.toInt, txIndex, outputIndex))
+  def apply(l: Long): ShortChannelId = UnspecifiedShortChannelId(l)
 
   def toShortId(blockHeight: Int, txIndex: Int, outputIndex: Int): Long = ((blockHeight & 0xFFFFFFL) << 40) | ((txIndex & 0xFFFFFFL) << 16) | (outputIndex & 0xFFFFL)
 
+  def generateLocalAlias(): Alias = Alias(System.nanoTime()) // TODO: fixme (duplicate, etc.)
+
   @inline
-  def blockHeight(shortChannelId: ShortChannelId): BlockHeight = BlockHeight((shortChannelId.id >> 40) & 0xFFFFFF)
+  def blockHeight(shortChannelId: ShortChannelId): BlockHeight = BlockHeight((shortChannelId.toLong >> 40) & 0xFFFFFF)
 
   @inline
-  def txIndex(shortChannelId: ShortChannelId): Int = ((shortChannelId.id >> 16) & 0xFFFFFF).toInt
+  def txIndex(shortChannelId: ShortChannelId): Int = ((shortChannelId.toLong >> 16) & 0xFFFFFF).toInt
 
   @inline
-  def outputIndex(shortChannelId: ShortChannelId): Int = (shortChannelId.id & 0xFFFF).toInt
+  def outputIndex(shortChannelId: ShortChannelId): Int = (shortChannelId.toLong & 0xFFFF).toInt
 
   def coordinates(shortChannelId: ShortChannelId): TxCoordinates = TxCoordinates(blockHeight(shortChannelId), txIndex(shortChannelId), outputIndex(shortChannelId))
 }
 
+/**
+ * A real short channel id uniquely identifies a channel by the coordinates of its funding tx output in the blockchain.
+ * See BOLT 7: https://github.com/lightningnetwork/lightning-rfc/blob/master/07-routing-gossip.md#requirements
+ */
+object RealShortChannelId {
+  def apply(blockHeight: BlockHeight, txIndex: Int, outputIndex: Int): RealShortChannelId = RealShortChannelId(toShortId(blockHeight.toInt, txIndex, outputIndex))
+}
+
 case class TxCoordinates(blockHeight: BlockHeight, txIndex: Int, outputIndex: Int)

eclair-core/src/main/scala/fr/acinq/eclair/balance/BalanceActor.scala

@@ -105,7 +105,7 @@ private class BalanceActor(context: ActorContext[Command],
           Metrics.GlobalBalanceDetailed.withTag(Tags.BalanceType, Tags.BalanceTypes.OnchainConfirmed).update(result.onChain.confirmed.toMilliBtc.toDouble)
           Metrics.GlobalBalanceDetailed.withTag(Tags.BalanceType, Tags.BalanceTypes.OnchainUnconfirmed).update(result.onChain.unconfirmed.toMilliBtc.toDouble)
           Metrics.GlobalBalanceDetailed.withTag(Tags.BalanceType, Tags.BalanceTypes.Offchain).withTag(Tags.OffchainState, Tags.OffchainStates.waitForFundingConfirmed).update(result.offChain.waitForFundingConfirmed.toMilliBtc.toDouble)
-          Metrics.GlobalBalanceDetailed.withTag(Tags.BalanceType, Tags.BalanceTypes.Offchain).withTag(Tags.OffchainState, Tags.OffchainStates.waitForFundingLocked).update(result.offChain.waitForFundingLocked.toMilliBtc.toDouble)
+          Metrics.GlobalBalanceDetailed.withTag(Tags.BalanceType, Tags.BalanceTypes.Offchain).withTag(Tags.OffchainState, Tags.OffchainStates.waitForChannelReady).update(result.offChain.waitForChannelReady.toMilliBtc.toDouble)
           Metrics.GlobalBalanceDetailed.withTag(Tags.BalanceType, Tags.BalanceTypes.Offchain).withTag(Tags.OffchainState, Tags.OffchainStates.normal).update(result.offChain.normal.total.toMilliBtc.toDouble)
           Metrics.GlobalBalanceDetailed.withTag(Tags.BalanceType, Tags.BalanceTypes.Offchain).withTag(Tags.OffchainState, Tags.OffchainStates.shutdown).update(result.offChain.shutdown.total.toMilliBtc.toDouble)
           Metrics.GlobalBalanceDetailed.withTag(Tags.BalanceType, Tags.BalanceTypes.Offchain).withTag(Tags.OffchainState, Tags.OffchainStates.closingLocal).update(result.offChain.closing.localCloseBalance.total.toMilliBtc.toDouble)

eclair-core/src/main/scala/fr/acinq/eclair/balance/CheckBalance.scala

@@ -77,13 +77,13 @@ object CheckBalance {
    * The overall balance among all channels in all states.
    */
   case class OffChainBalance(waitForFundingConfirmed: Btc = 0.sat,
-                             waitForFundingLocked: Btc = 0.sat,
+                             waitForChannelReady: Btc = 0.sat,
                              normal: MainAndHtlcBalance = MainAndHtlcBalance(),
                              shutdown: MainAndHtlcBalance = MainAndHtlcBalance(),
                              negotiating: Btc = 0.sat,
                              closing: ClosingBalance = ClosingBalance(),
                              waitForPublishFutureCommitment: Btc = 0.sat) {
-    val total: Btc = waitForFundingConfirmed + waitForFundingLocked + normal.total + shutdown.total + negotiating + closing.total + waitForPublishFutureCommitment
+    val total: Btc = waitForFundingConfirmed + waitForChannelReady + normal.total + shutdown.total + negotiating + closing.total + waitForPublishFutureCommitment
   }
 
   def updateMainBalance(localCommit: LocalCommit): Btc => Btc = { v: Btc =>
@@ -201,7 +201,7 @@ object CheckBalance {
     channels
       .foldLeft(OffChainBalance()) {
         case (r, d: DATA_WAIT_FOR_FUNDING_CONFIRMED) => r.modify(_.waitForFundingConfirmed).using(updateMainBalance(d.commitments.localCommit))
-        case (r, d: DATA_WAIT_FOR_FUNDING_LOCKED) => r.modify(_.waitForFundingLocked).using(updateMainBalance(d.commitments.localCommit))
+        case (r, d: DATA_WAIT_FOR_CHANNEL_READY) => r.modify(_.waitForChannelReady).using(updateMainBalance(d.commitments.localCommit))
         case (r, d: DATA_NORMAL) => r.modify(_.normal).using(updateMainAndHtlcBalance(d.commitments, knownPreimages))
         case (r, d: DATA_SHUTDOWN) => r.modify(_.shutdown).using(updateMainAndHtlcBalance(d.commitments, knownPreimages))
         case (r, d: DATA_NEGOTIATING) => r.modify(_.negotiating).using(updateMainBalance(d.commitments.localCommit))

eclair-core/src/main/scala/fr/acinq/eclair/balance/Monitoring.scala

@@ -44,7 +44,7 @@ object Monitoring {
 
     object OffchainStates {
       val waitForFundingConfirmed = "waitForFundingConfirmed"
-      val waitForFundingLocked = "waitForFundingLocked"
+      val waitForChannelReady = "waitForChannelReady"
       val normal = "normal"
       val shutdown = "shutdown"
       val negotiating = "negotiating"